The SOAR Goodman Spectrograph Red Camera is equipped with a 4096 x 4112 pixel, back-illuminated, deep-depletion, astro-multi-2 coating, e2v 231-84 CCD.  The CCD is read out through 1 amplifier using a Spectral Instruments [8] controller.  This CCD has excellent cosmetics.  Figure 1 shows a bias frame obtained in Spectroscopic 1x1 ROI mode and with the 344ATTN3 readout (Gain=1.48 e-/ADU, Readout Noise=3.89 e-). Figures 2 and 3 show a dome quartz lamp flat for the 400 l/mm grating in the 400M2 setup (505-905 nm).  Note the almost complete lack of fringing at the red end of the image, compared to the Blue Camera CCD [1] (Figure 4).

Figure 1. Goodman Red Camera bias frame (ROI: Spectroscopic 1x1; Readout: 344ATTN3)

Figure 2. Goodman Red Camera Dome Flat. Grating: 400, Mode: M2 + GG455 filter, ROI: Spectroscopic 1x1, Readout:344ATTN3, Dome lamps at 100%, Texp=20s

Figure 3. Plot of the above dome flat, along the wavelength direction (averaged 10 pixels across the spatial direction). Redder wavelengths to the right.

Figure 4. Comparison of dome flats obtained with the Blue and Red cameras, normalized at 5000A, using the 400M2+GG455 grating setup and 1.03 arcsec slit.

Click on this link for a PDF version of this info sheet [9]

We have obtained observations of standard stars in order to determine the system throughput with the Red Camera. Results will be posted soon.

Goodman Red Camera Cold Start page [10]

The SOAR Goodman Spectrograph Blue Camera features one 4096 x 4096 pixel Fairchild CCD.  The CCD is read out through 1 amplifier using a Spectral Instruments [8] controller.  This CCD has only minor flaws which has little impact on its scientific performance.  Figure 1 shows the combination of 20 bias frames taken with the 200ATTN0 readout mode (Readout Noise= 4.74 e-, Gain=1.4 e-/ADU), with the Spectroscopic 1x1 ROI.

Figure 1. Combined Bias frames in Spectroscopic 1x1 mode (average of 20 individual bias taken with the 200ATTN0 readout mode).

Figure 2 below shows an internal quartz lamp flat for the 400 l/mm grating in the 400M2 setup (505-905 nm).  Note the fringing pattern at the red end of the image. 

Figure 2: An internal quartz lamp flat of the 400l/mm grating in the 400M2 setup, taken with a Multi-Object Slit (MOS) Mask, The upper two and lower srtpes correspond to the square boxes for the alignment stars. The middle stripes are the quartz flats produced with the four science target slits.

Figure 3 shows the QE of the Goodman Blue Camera CCD.

Figure 3:  The QE curve of the Goodman CCD.

Below we provide the general characteristics of the Blue Camera detector and the available readout modes:

The default image size for imaging mode (1x1 binning) is 3096 x 3096 pixels and the default image size for spectroscopic mode is 4142 x 1896 pixels with 1x1 binning. These values were used calculate the read out times given above using one amplifier readout. Users should also expect 1 or 2 seconds of overhead on every exposure. 

Throughput: 
The imaging mode throughput of the GOODMAN BLUE CAMERA has been measured relative to the SOAR Optical Imager (SOI) for which we have good zero-points. As the table below shows, the throughput relative to SOI is better in the R, comparable in the V and lower in the B and U.
 
In the Goodman Throughput Information [3] page we show the measured the spectroscopic throughput of the Goodman BLUE CAMERA, obtained by taking spectra of spectrophotometric standards with the most commonly used preset setups. These curves show the overall system efficiency for the telescope+instrument+detector combination, with and without the Atmospheric Dispersion Corrector (ADC), commissioned in late 2014. That is, they show the fraction of photons striking the primary mirror of SOAR which are eventually detected by the CCD. The measurements were made using a very wide (~10 arcsec slit); slit losses will reduce the efficiency obtained when using a narrower slit by an amount which depends on the seeing. The measurements are corrected for atmospheric extinction; the efficiency obtained in an actual observation will be reduced by the atmospheric extinction for the airmass of observation.

Goodman Blue Camera Cold Start page [11]

Updated Mar 2021.

Up to three (3) gratings can be installed in the spectrograph at a time, in a linear stage which allows the rapid interchange of gratings. Installing different gratings is a day time operation. No grating installations are done during the night.

• 1200 line gratings: For observations in the UV use the 1200Blue grating + Blue Camera. Observations in the 450nm - 550nm range should use the 1200Blue grating, with either Blue or Red Cameras. For observations redward of ~600nm, use the 1200Red grating + Red Camera.

Configurations remain as listed in the table below.

Long Wavelength Limit for High Resolution Gratings
Because of limits in the camera rotation stage, it is not possible to use the 1800, 2100 and 2400 l/mm gratings beyond the central wavelengths indicated below:

• 1800 l/mm grating: Littrow mode centered at 760nm, spans 7200 A - 8000 A
• 2100 l/mm grating: Littrow mode centered at 650nm, spans 6185 A - 6815 A
• 2400 l/mm grating: Littrow mode centered at 565nm, spans 5395 - 5905 A

The table below shows the dispersion and the wavelength coverage for observations in our set spectroscopic modes.  Please note that the 1800, 2100, and 2400 l/mm gratings are operated in Custom mode (Littrow Configuration), in which the observer selects the central wavelength for their observations.

The VPH gratings operate via Bragg scattering and their efficient operation requires Littrow or near-Littrow operation of the spectrograph. A grating rotation stage sets the incident angle to the desired value, which depends upon the line density of the grating and the central wavelength of interest. A concentric camera rotation stage must then be set to nearly twice this angle to intercept the diffracted beam.  A set of fixed observing modes for each grating are given below, where applicable.  All gratings can be used in the Custom mode.

The Goodman High Throughput Spectrograph (GHTS) has an assortment of long slits from which the user can choose, in addition to the possibility of creating custom Multi-Object Slit (MOS) masks.

The GHTS has a carrousel with 36 positions, of which 27 are available for longslits and/or Multi-Objects Masks (MOS).   Each long slit is approximately 3.9 arcmin long.
As of Aug 23, 2017, long slits which are always installed and available are the folllowing (all widths in arcsec; the unbinned pixel scale of the GHTS is 0.15 arcsec/pixel):

0.45", 0.6", 0.8", 0.95", 1.0", 1.2", 1.5", 1.9", 3.2", 4" and 10.2". 

The following table provides the old names of some of the slits.

We have 16 remaining positions are available for MOS masks. Installing MOS masks is a daytime task, like changing filters, and should be requested beforehand in the Instrument Setup Form [12], or by email to the Support Astronomer with copy (cc) to soarops@ctio.noao.edu [13], so our Observer Support staff also receives the request.

Note: the Goodman Acquisition Camera (GACAM) [14] has a FOV=1.8arcmin in its longest dimension, therefore, it does not span the full length of a Goodman long slit. If your science requires a full view of the long slit you will need to use the pre-imaging procedure for object acquisition (see the Step-by-step guide to Observing with Goodman [15]).